Simplify ThreatBySafePawn evaluation

[stockfish] / src / evaluate.cpp

diff --git a/src/evaluate.cpp b/src/evaluate.cpp
index 64e0eca40d748b335086d40100906ddd718fcd62..e39bcb4a8e99721820fa637151ace370d009f5d9 100644 (file)
--- a/src/evaluate.cpp
+++ b/src/evaluate.cpp
@@ -28,8 +28,7 @@
 #include "evaluate.h"
 #include "material.h"
 #include "pawns.h"
-
-std::atomic<Score> Eval::Contempt;
+#include "thread.h"
 
 namespace Trace {
 
@@ -275,6 +274,12 @@ namespace {
         if (relative_rank(Us, pos.square<KING>(Us)) == RANK_1)
             kingRing[Us] |= shift<Up>(kingRing[Us]);
 
+        if (file_of(pos.square<KING>(Us)) == FILE_H)
+            kingRing[Us] |= shift<WEST>(kingRing[Us]);
+
+        else if (file_of(pos.square<KING>(Us)) == FILE_A)
+            kingRing[Us] |= shift<EAST>(kingRing[Us]);
+
         kingAttackersCount[Them] = popcount(attackedBy[Us][KING] & pe->pawn_attacks(Them));
         kingAttacksCount[Them] = kingAttackersWeight[Them] = 0;
     }
@@ -289,7 +294,7 @@ namespace {
 
     constexpr Color Them = (Us == WHITE ? BLACK : WHITE);
     constexpr Bitboard OutpostRanks = (Us == WHITE ? Rank4BB | Rank5BB | Rank6BB
-                                               : Rank5BB | Rank4BB | Rank3BB);
+                                                   : Rank5BB | Rank4BB | Rank3BB);
     const Square* pl = pos.squares<Pt>(Us);
 
     Bitboard b, bb;
@@ -368,7 +373,7 @@ namespace {
 
         if (Pt == ROOK)
         {
-            // Bonus for aligning rook with with enemy pawns on the same rank/file
+            // Bonus for aligning rook with enemy pawns on the same rank/file
             if (relative_rank(Us, s) >= RANK_5)
                 score += RookOnPawn * popcount(pos.pieces(Them, PAWN) & PseudoAttacks[ROOK][s]);
 
@@ -406,7 +411,7 @@ namespace {
 
     constexpr Color    Them = (Us == WHITE ? BLACK : WHITE);
     constexpr Bitboard Camp = (Us == WHITE ? AllSquares ^ Rank6BB ^ Rank7BB ^ Rank8BB
-                                       : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);
+                                           : AllSquares ^ Rank1BB ^ Rank2BB ^ Rank3BB);
 
     const Square ksq = pos.square<KING>(Us);
     Bitboard weak, b, b1, b2, safe, unsafeChecks, pinned;
@@ -515,17 +520,13 @@ namespace {
 
     // Non-pawn enemies attacked by a pawn
     nonPawnEnemies = pos.pieces(Them) ^ pos.pieces(Them, PAWN);
-    weak = nonPawnEnemies & attackedBy[Us][PAWN];
 
-    if (weak)
-    {
-        // Our safe or protected pawns
-        b =  pos.pieces(Us, PAWN)
-           & (~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES]);
+    // Our safe or protected pawns
+    b =   pos.pieces(Us, PAWN)
+       & (~attackedBy[Them][ALL_PIECES] | attackedBy[Us][ALL_PIECES]);
 
-        safeThreats = pawn_attacks_bb<Us>(b) & weak;
-        score += ThreatBySafePawn * popcount(safeThreats);
-    }
+    safeThreats = pawn_attacks_bb<Us>(b) & nonPawnEnemies;
+    score += ThreatBySafePawn * popcount(safeThreats);
 
     // Squares strongly protected by the enemy, either because they defend the
     // square with a pawn, or because they defend the square twice and we don't.
@@ -687,7 +688,7 @@ namespace {
             }
             else if (pos.pieces(Us) & blockSq)
                 bonus += make_score(w + r * 2, w + r * 2);
-        } // rr != 0
+        } // w != 0
 
         // Scale down bonus for candidate passers which need more than one
         // pawn push to become passed or have a pawn in front of them.
@@ -795,11 +796,10 @@ namespace {
     {
         if (pos.opposite_bishops())
         {
-            // Endgame with opposite-colored bishops and no other pieces (ignoring pawns)
-            // is almost a draw, in case of KBP vs KB, it is even more a draw.
+            // Endgame with opposite-colored bishops and no other pieces is almost a draw
             if (   pos.non_pawn_material(WHITE) == BishopValueMg
                 && pos.non_pawn_material(BLACK) == BishopValueMg)
-                sf = more_than_one(pos.pieces(PAWN)) ? 31 : 9;
+                sf = 31;
 
             // Endgame with opposite-colored bishops, but also other pieces. Still
             // a bit drawish, but not as drawish as with only the two bishops.
@@ -838,7 +838,7 @@ namespace {
     // Initialize score by reading the incrementally updated scores included in
     // the position object (material + piece square tables) and the material
     // imbalance. Score is computed internally from the white point of view.
-    Score score = pos.psq_score() + me->imbalance() + Eval::Contempt;
+    Score score = pos.psq_score() + me->imbalance() + pos.this_thread()->contempt;
 
     // Probe the pawn hash table
     pe = Pawns::probe(pos);
@@ -909,7 +909,7 @@ std::string Eval::trace(const Position& pos) {
 
   std::memset(scores, 0, sizeof(scores));
 
-  Eval::Contempt = SCORE_ZERO; // Reset any dynamic contempt
+  pos.this_thread()->contempt = SCORE_ZERO; // Reset any dynamic contempt
 
   Value v = Evaluation<TRACE>(pos).value();